The electronic operation of reciprocating piston engine valves such as internal combustion engine valves offers the potential of advancing or retarding valve actuation (phase control) as well as the possibility of electronically tailoring the valve opening and closing time within each cycle of operation by means of the engine control unit computer to reach performance goals such as reduced fuel consumption that are unobtainable with variable camshaft phasing currently used for example in cars and trucks.
Several electrical and hydraulic systems have been proposed but none have been commercially successful with regard to cost and performance. Fully electric designs exemplified by U.S. Pat. Nos. 4,829,947; 6,220,210 and 6,237,550 have been proposed but have not been adapted for wide sale commercial use. The same is true of electrohydraulic internal combustion valve actuators such as those described in U.S. Pat. Nos. 5,509,637; 4,009,695; 6,604,497; 4,878,464; 4,974,495; 6,089,197; 7,063,054 or 7,347,171. Steam engine valves have been actuated by an electromagnet and by steam, e.g., U.S. Pat. No. 8,448,440 but steam is not available in cars or trucks and there is no internal combustion (I.C.) valve nor any recognition in the patent of applicability or benefit concerning internal combustion engines.
Existing I.C. valve actuator systems ordinarily require a heavy duty engine valve closing spring for applying a force of typically about 300 lb.-1000 lb. together with one or more solenoid operated hydraulic valves each connected by ducts to a hydraulic actuator piston which is, in turn, connected to the engine intake or exhaust valve. Besides being complicated in construction, the heavy valve seating springs can reduce valve cycling speed and contribute to valve actuator power requirements which are a function of the product of spring stiffness and the square of the valve lift.
In view of these and other deficiencies found in previous reciprocating engines such as internal combustion engine valves and actuators such as those proposed for use in vehicles, e.g., cars and trucks, it is a general object of the present invention to find a mechanically simplified yet more effective way to employ electric control of a fluid (gas such as air or a liquid) for regulating the opening and closing of internal combustion (I.C.) engine valves at different selected time intervals.
Another object is to be able to open and close I.C. valves at a significantly faster rate than is accomplished by the harmonic action of a camshaft.
Another object is to find a way to actuate I.C. valves using electronic triggering that is capable of operating the I.C. valves with variable phase control at a cycling rate of at least 60 Hz (7200 rpm for a four-stroke engine).
Still another object is to provide a fluid actuated I.C. valve in which fluid at supply pressure applies a selected I.C. opening force followed by a closing force great enough to achieve an abrupt closing action.
Still another object is to provide electromagnetic valve actuation with a significant valve lift, e.g., 10 mm or ⅜ inch, yet provide a magnetic traction force to initiate valve motion that is not significantly diminished by being applied in an area of reduced magnetic flux density.
Another object is to provide I.C. engine in which I.C. valve closing motion is initiated electrically and is continued in the same direction by the application of fluid pressure
Another object is to begin closure of the I.C. valve electrically and to open the valve by the application of fluid pressure at the end of a separately determined time period.
Another object of the invention is to operate I.C. engine valves using a single signal, e.g., an electrical current sufficient to initiate timed valve closure in which the timed opening step that follows continues automatically without a need to either engage further mechanical elements or provide added electronic input.
Yet another object of the invention is to close each I.C. valve entirely or almost entirely by fluid pressure rather than by using a heavy valve spring of the kind commonly found in I.C. engines thereby eliminating the resistance of a typical valve spring, reducing valve work and achieving higher cycling rates.
These and other more detailed and specific object and advantages of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims
All citations listed herein are incorporated herein by reference as fully and completely as if reproduced herein in their entirety and specifically indicated to be incorporated.